Here is a copy of the layout of a roo full sheet taken from The Kangaroo Issues by H Dormer Legge

This is a full sheet of 480-on which was four plates clamped together (each plate contained 2 panes of sixty). It was used for printing the early 1d Roos in this configuration. For later 1d and other low values sheets were cut down the middle and printed 240-on from 2 plates. The higher value bi-colour issues were printed 120-on from one plate of 2 panes.
The layout of the KGV paper with second watermark or single watermark was the same.
By using this information it is possible to plate some stamps with marginal watermarks according to the letter showing. This layout applies only to the first, second and third watermarks. Later watermarks did not show marginal markings.
First and third watermark paper was designed for use with the Roos. Second watermark paper was slightly larger and designed for use with KGV. It was trimmed and used for limited numbers of Roos when delivery of the third watermark paper was delayed.
Regards
Frank